Installing wall-to-wall carpeting generally requires the installation of carpet retaining wood strips (also called “tackless strips” or “tack strips”). These tack strips are nailed into the flooring adjacent to walls in a room to be carpeted. One edge of the carpet is then secured to tacks extending from the strip. The carpet is then stretched so that the opposite edge can be secured to the tack strip on the other side of the room. This method of installation helps to ensure that the carpet will not buckle or form bumps.
A carpet stretching tool is used to stretch the carpet between the tack strips. FIG. 1 illustrates a typical conventional carpet stretching tool, such as the Power Stretcher tool sold by Crain Tools. The illustrated carpet stretching tool includes a carpet gripping head 62 having carpet engaging pins 66. Adjusting knob 68 on head 62 allows adjustment of pin depth, allowing for gripping at various depths of shag carpet or carpet piles. Carpet engaging head 62 is mounted on square bar 74, which is slidably mounted within tube 72. At the end of tube 72 is mounted tail section 8. Tail section 8 may be mounted using a tail tube section 14 mounted onto the main tube 72 by a spring clip inserted at the open end of tube 14, the buttons 19 of said spring clip extending through holes 30 in main tube 72. Extending from tube 72 are transfer bars 70. Transfer bars 70 are mounted at a pivot point on both ends of transfer bar 70 to both the tube 72 and handle 60, respectively. At the end of handle 60 is grip 64. The tail section 8 has a flat surface that presses against the wall where the carpet is already secured. The pins 66 on carpet gripping head 62 then grip the carpet proximate to the edge of the carpet opposite the tail. Handle 60 is then depressed, causing gripping head 62 to extend away from tube 72. This extends head 62 from tail section 8, thereby stretching the carpet. The carpet is stretched to the location of the tack strips on the second side of the room. Once the carpet is secured, the tail section may be rolled along the wall using wheels 7. The tool may be rolled after pins 66 have been disengaged from the carpet.
In the process of using this carpet stretching tool, the installer begins at one corner of the room, placing the tail against a first wall proximate to a corner and extending the elongate body of the tool such that the carpet gripping head grips the carpet near the edge on the opposite side of the room. The tool is then used to produce leverage, thereby stretching the carpet. The edge of the carpet proximate to the head is attached to the tack strip. The head is then disengaged from the carpet and the tail end is slid or rolled a distance down the floor against the first wall. Rollers on the tail may aid in moving the tool down a wall. This process is then repeated.
The tail section 8 of a conventional carpet stretching tool, shown in FIG. 1, has a generally flat surface on its back side where it presses against a wall. It works well against straight, flat wall surfaces and when the carpet to be stretched is more or less straight across the room from the current position of tail section 8. However, some carpet installations are performed in “L” shaped living room/dining room areas, which are common in modern “open floor plan” home layouts. In such “L” shaped living room/dining rooms, the installer will desire to brace the tail section off an inner wall until reaching an outside corner. The reason an inner wall is preferred is that on the outer wall, doors (such as sliding glass doors), are often encountered. Such doors are not suitable to support tail section 8. Once the outside corner is reached, the installer must angle head 62 and elongate tube sections to reach further across the room and into the opposite corner of the room. However, the more that head 62 and elongate tube sections are angled, the more a horizontal force transfers to the back surface of tail section 8. Eventually, the tail section 8 will slip horizontally and will no longer function. The installer must a) have a helper keep a foot on the tail block to stop it from slipping or b) get more extension tubes and press the tail section against a different wall. Neither option is convenient and both add costs to installation. If tail section 8 could somehow be braced against the outside corner in such a manner that prevents slipping, the installer could continue stretching in a fan-like pattern all the way into the corner of the opposite wall and beyond out of the corner until the elongate tubes extending from head 62 were again more or less perpendicular to the opposite wall surface (at which point the flat surface of tail section 8 would no longer slip). While the stretcher would be used in this “fan pattern,” it is desirable that the back surface of tail section 8 stay in the corner, but the elongate tube section would need to pivot from this fixed position to accomplish the desired fanning motion for the head 62.
Also, in homes having basements, there is typically a support post in the center of these basements. The post is sturdy and tail section 8 could be butted up against it for stretching. However, the posts encountered in basements are commonly cylindrical. The flat back surface of tail section 8 will slip if the elongate tube section is at any angle other than a right angle to the back surface of tail section 8. In this situation, it would be desirable if the elongate tube section were fixed perpendicularly to the back surface of tail section 8, not pivoting as it normally does. It would also be desirable that tail section 8 formed some other shape so that it would not slip, as the curved surface of a round post provides little traction for a tail section 8 with an elongated flat surface.
A number of prior art devices have been developed to address the installation of carpet in various shaped rooms, and to allow carpet stretcher tail sections to be used on surfaces which are not straight, flat wall surfaces. For example, U.S. Pat. No. 3,706,440 to Ross discloses a tail section for a carpet stretcher. The tail section has a pivotably mounting adapter tube to connect with an elongate tube section. The tail section has two vertically extending surfaces for abutting a wall forming an included angle, this angle being about 90 degrees, allowing it to be used at an outside corner surface. This device also has horizontal surfaces extending from the ends of the vertical surfaces. These horizontal surfaces allow use of the tail section against straight, flat walls.
The tail section device of the Ross patent has a number of drawbacks. The included angle vertical surfaces are just used for holding the device at a corner location and the horizontal surfaces are just used on flat wall surfaces. The tail section must be relatively large to include both the specified vertical and horizontal surfaces. Such a large tail section makes the tool more expensive, heavy, and bulky. Such a bulky tail section is difficult to fit inside a carrying case. Most modern carpet stretcher tools are sold with a carrying case that holds all tool components. Furthermore, the attachment of the tail section is at the apex of the included angle. When the tail section is used on a flat surface, the central area of the tail section (between the two horizontal surfaces) creates a gap where the tail is not in contact with the wall. The force generated by the stretching components will transfer to the tail section at the apex of the included angle where the elongate tube body is attached to the tail section. When the tail section is used on a flat wall, the force will be concentrated at the inner edges of the horizontal surfaces. This concentrated force could mar wall surfaces. Finally, the Ross device has no mechanism to lock the tail section with respect to the elongate tubes. This can limit the usefulness of the carpet stretcher tool.
U.S. Pat. No. 3,747,157 to Szymanski discloses a carpet stretcher having a carpet engaging head mounted on a tubular body. At the end of this tubular body, an adapter to the stretcher is formed by two spaced parallel triangular plates. The two plates are pivotably mounted to the stretcher by way of a registering hole and a connecting pin which runs through the stretcher tube. Along two sides of the triangular plates up to two elongate tube sections may be pivotably mounted with similar register holes and connecting pins. Thus, one of the elongate tube sections may be pivoted in a direction where it abuts against a wall surface near an outside corner, and the other may be pivoted in a direction such that it abuts a second adjacent wall, thereby preventing slippage of the tail section at the outside corner. U.S. Pat. No. 3,752,440 to Ream discloses a similar adapter which uses three short, permanently-mounted pivoting adapter tubes (rather than holes and pins) to connect to the stretcher and elongate tube sections. Also disclosed are a plurality of available tail sections for engaging the wall on the end of the elongate tube sections, one of which is “L” shaped for outside corners. U.S. Pat. No. 5,176,387 to Taggart discloses yet another similar adapter with a “T” shaped bracket. One leg of the T attaches rigidly into the stretcher tube. The other two legs have pivoting mounts for adapter tubes which may be connected to the elongate tube sections. In this device, the tail sections may pivot as they abut the wall surfaces. This configuration allows this type of adapter to be used in long hallways.
Common problems with all these adapters with pivots for an additional elongate tube section are as follows. First, they are a costly additional accessory to the basic carpet stretcher. Second, the user may not own the additional elongate tube sections (such as would be required for tools having two additional legs) and have to purchase them along with an additional tail section. Third, it is inconvenient to carry these additional components on the jobsite. Lastly, such devices are not designed for stretching using posts.
U.S. Pat. No. 4,730,858 to Humann discloses an “S” shaped adapter intended to work with commonly available carpet stretcher tail sections. One end of the adapter hooks over the outside corner surface of the walls. The other corner extends from the wall and creates a stop that prevents slipping of the tail section. Again, this is a costly separate adapter which must be carried on the jobsite, and is useful only for outside corners.
U.S. Pat. No. 4,538,846 to Alexander discloses a plurality of brace assemblies which may connect to the end of an elongate tube section, and are “U” shaped to abut and fit around various diameter round and square posts. With respect to their relation to the elongate tube section they are meant to be attached to, some of the “U” shaped brace assemblies are designed to pivot, some are designed to pivot and lock at certain points, and others are designed without any ability to pivot. These devices are useful only for stretching off posts.
U.S. Pat. No. 5,855,361 to Krowchak discloses a tail section similar to the one disclosed in U.S. Pat. No. 3,706,440 to Ross. This tail section has a pivoting adapter tube. The tail section's wall-abutting surface has two vertically extending surfaces forming an included angle of 90 degrees for stretching off outside corners. Within this included angle, a hook adapter may be inserted. This hook adapter pokes through the carpet and hooks into the subfloor. The hook provides a stop for the stretcher. The elongate tube section which would normally extend to the wall is no longer needed. This tail section also includes a lock pin which extends through the adapter tube. Thus, the included angle may engage posts, and the elongate tube section may be locked as desired. All of the above references are hereby incorporated by reference herein.
The problems with this tail section are as follows: First, the 90 degree angle formed in the tail section results in a large, bulky tail component. Second, the locking pin for the elongate tube section runs directly through the pivoting tube. In most carpet stretching tools the pivoting tube is preferably made from a steel tube. The holes in a steel tube may elongate and become imprecise when subjected to side loads by the steel pin. This is because the walls of the steel tube are thin. As the holes elongate, the tail block will no longer hold the desired perpendicular angle with the elongate tube section and will rattle. Furthermore, the thin walls of the steel tube will scratch and burr the pin. Pin holes are preferably created in a softer, solid material (such as an aluminum casting). In contrast, the bearing holes for the pin are thick and precisely reamed and can thus totally support the pin.
In the Krowchak reference, the tail section itself is said to be pivotably mounted directly to the end of a tubular member by way of a similar pin. Under pressure from the elongate tube section, the pin would press against holes in the tubular member, and the holes in the tubular member would elongate. The motion of the pivoting tube would become imprecise and would bind as burs were worn in the pin by the tube.
Lastly, the tail section is not supported in the area of the 90 degree included angle. Yet this area bears most of the pressure from the elongate tube section. As a result, the tail section may leave an impression or mark on the wall at the edges of the horizontal tail section.